Getting the design right

Whilst green roofs have been around since biblical times, the development over recent years of the lightweight systems which are now most commonly used in the United Kingdom has led to a substantial increase in the number of buildings where it is practical to consider their use.

Types of green roof

The term “extensive” is applied to lightweight, low maintenance installations where access is generally required for maintenance purposes only. The mix of vegetation will vary from sedum through to drought tolerant wild flowers, herbs, alpines and grasses and may also include some hardy shrubs and perennials. The substrate depth, irrigation and maintenance requirements will vary significantly, dependent upon the type of vegetation specified and its purpose, but will be significantly less than those for intensive green roofs. More ►

This specific type of ‘living’ roof typically either tries to replicate as closely as is practical the ecological environment of the site where construction has taken place or sets out to create a natural habitat to support a variety of plants, birds, animals and invertebrates. More ►

A traditional intensive green roof installation can best be described as one which is intended to mimic the appearance of a traditional amenity landscape, such as a park, terrace or garden. It is often constructed over the roof of a “buried” structure and can be blended into the surrounding landscape. Whilst the hard landscaping and vegetation can be whatever the client wishes, the height to which the plants and trees are required to grow will determine the depth of growing medium, the level of irrigation required and the planned maintenance needed to keep it looking in good order. More ►

Hard landscaping with planters for vegetation designed for continual access without the high levels of maintenance that are associated with an intensive green roof design. More ►

When planning to specify a green roof the key considerations should be:

What purpose is the green roof to serve?

What is the visual requirement?

What level of access will be required?

What load will the structure support?

How is the green roof system to drain?

What is the budget for the installation?

What is the budget for maintenance?

Once the answers to the above have been decided upon it is a relatively simple process to consider the range of suitable options and determine which is best suited to the project requirement. More information ►

Your local technical manager is best placed to advise you on the implications your green roof will have on the building and its construction as well as the ongoing maintenance of the vegetation and roof. CallDan Taylor, 0845 271 8800, to arrange a conversation either by phone or at your office with your technical advisor.